Compositional and functional properties of fractions rich in milk fat globule membrane material
Compositional and functional properties of three fractions rich in milk fat globule membrane material were studied. The isolates--designated washed cream buttermilk (WBM), MFGM, and whey retentate (WR)--were prepared by churning butter from water-washed cream and collecting the buttermilk, by extensive membrane filtration of buttermilk through 1.4 [mu]m ceramic membranes in the presence of sodium citrate, and by concentration of buttermilk from whey cream through 0.1 [mu]m PVDF membranes, respectively. MFGM had the highest purity of membrane proteins and phospho lipids with WR almost as pure. WBM resembled commercial buttermilk still high in caseins. MFGM and WBM emulsions showed antioxidant activity over control emulsions, while WR emulsions provided little oxidative protection. When emulsions were mixed with skim milk and rennet-induced gels were prepared, different behaviours during renneting were observed. Recombined milks containing MFGM emulsions created stiffest gels with earliest gel onset times, while WR emulsions created gels with lowest stiffness.